Thursday, 17 January 2002: 10:57 AM
Global Estimates of the Diurnal Cycle of Rainfall from a Trmm-Calibrated Infrared Rainfall Algorithm
We present the development of a satellite infrared (IR) technique for estimating convective and stratiform rainfall and its application in studying the diurnal variability of rainfall on a global scale. The Convective-Stratiform Technique, calibrated by coincident physically retrieved rain rates from the TRMM Precipitation Radar (PR) is applied during 2000 from 30N to 30S latitudes. The technique is calibrated separately over different seasons and a number of geographical regions. The diurnal cycle of rainfall, as well as the division between convective and stratiform rainfall will be presented. Previous work used IR data from GOES, calibrated with rainfall estimates from the TRMM Microwave Imager (TMI). This technique was validated over Amazon region using in situ radar. Estimates from this new PR-calibrated technique will be compared to other global rainfall products such as GPCP monthly and daily precipitation products. The low sampling rate of TRMM PR definitely imposes limitations on calibrating IR-based techniques. We demonstrate however that PR observations can be applied to significantly improve IR-based techniques by careful selection of calibration areas and lengths of calibration periods.